Invited Presenter

Briana K. Whitaker ¹, Imane Laraba ², Christina Cowger ³, Pete Oppenheimer ⁴, Susan McCormick ¹, Mark Busman ¹, and Martha Vaughan ¹
1. USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Mycotoxin Prevention & Applied Microbiology Unit, Peoria, IL
2. Agriculture and Agri-Food Canada, Ottawa, ON, Canada
3. USDA, Agricultural Research Service, Plant Science Research Unit, Raleigh, NC
4. North Carolina State University, Department of Entomology and Plant Pathology, Raleigh, NC
Corresponding Author: Briana Whitaker, Briana.whitaker@usda.gov

Briana Whitaker

Fusarium head blight (FHB) is an economically important disease of small grains globally and is primarily caused by species in the genus Fusarium. Although the deoxynivalenol- (DON) producing F. graminearum is often considered to be the primary causal agent of concern in N. America, other species or chemotypes can be more frequent in certain geographic regions or during certain years. In particular, little is known about Fusarium diversity in scabby U.S. wheat and barley spikes, nor about the environmental factors that cause local outbreaks of “emerging mycotoxin” producers (e.g., the F. tricinctum species complex). Thus, we are conducting surveys of Fusarium and mycotoxin diversity in FHB symptomatic wheat and barley to better understand the environmental factors driving higher frequencies of minority species, and emerging mycotoxins of concern. In 2022, we sampled 19 Illinois hard red winter wheat farms, isolated Fusarium from symptomatic heads, and quantified mycotoxin concentrations of scabby heads. In total, we isolated 1192 strains, which ranged from 10-82 per field. Most of the successfully isolated strains came from heads with low disease (<20% infected spikelets) and only a single visible point of infection. From TEF-1α partial sequencing, most isolates belonged to the Fusarium sambucinum species complex (>95% of isolates), with the remaining belonging to the Fusarium tricinctum, fujikuroi, and incarnatum-equiseti species complexes. Mycotoxin analyses revealed greater than expected concentrations of nivalenol (NIV) and culmorin (CUL) present in scabby wheat heads from southern Illinois. In particular, we found up to 14 μg of NIV per gram of grain material and up to 20 μg of CUL per gram of grain material in some fields. By contrast, we only found up to 2 μg of DON per gram of grain material across all 19 fields. A strong correlation was detected between NIV and CUL and is suggestive of the presence of Fusarium strains capable of producing both CUL and NIV. Ultimately, this indicates that there may be a significant proportion of NIV-producing F. graminearum in Illinois.